Functional mitral regurgitation is believed to result from the absence of coaptation of the mitral valve leaflets without any mitral valve disease. It is a risk factor of dilated cardiomyopathy and ischemic cardiomyopathy as a consequence of ventricular remodeling and dilation of the valvular annulus, and/or papillary muscle dysfunction. Modification of the geometry of the left ventricle by the tethering force of the papillary muscle is believed to be a significant cause of mitral valve regurgitation during dilated cardiomyopathy, while papillary and left ventricular dysfunction appears to be a significant cause of mitral valve regurgitation when myocardial ischemia is present (See e.g., T. Kono et al., “Left ventricular shape as a determinant of functional mitral regurgitation in patients with severe heart failure secondary to either coronary artery disease or idiopathic dilated cardiomyopathy” Am. J. Cardiol. 68(4):355-359 (1991); A. C. Hueb et al., “Ventricular remodeling and mitral valve modifications in dilated cardiomyopathy: new insights from anatomic study” J. Thorac. Cardiovasc. Surg. 124(6):1216-1224 (2002); and R. W. Godley et al., “Incomplete mitral leaflet closure in patients with papillary muscle dysfunction” Circulation 63(3):565-571 (1981).). Ventricular dilation increases the tethering on the chordea and changes the papillary angle, resulting in a reduction of the area of coaptation of the valve leaflet. With further dilation of the left ventricle the valve leaflets cannot make effective contact and regurgitation occurs (See, e.g., S. F. Bolling, “Mitral reconstruction in cardiomyopathy” J. Heart Valve Dis. 11, Suppl. 1:S 26-31 (2002).).
Coaptation of the mitral valve leaflet must be reestablished to prevent deterioration of cardiac function. Mitral valve annuloplasty using an undersized ring to provide leaflet coaptation in patients with cardiomyopathy has been shown to provide improved survival and good palliation of dilated cardiomyopathy and ischemic cardiomyopathy. However, this procedure requires cardiopulmonary bypass which results in a high mortality rate for patients. Additionally, undersized annuloplasty does not treat the underlying problem of tethering on the mitral valve and sphericity of the heart, and places the patient at greater risk for further heart dilation and deterioration of cardiac function.
In “Changes in mitral annular and left ventricular dimensions and left ventricular pressure-volume relations after off-pump treatment of mitral regurgitation with the Coapsys device” by K. Fukamachi et al., Eur. J. Cardiothorac. Surg. 25(3):352-357 (2004), the authors describe a device which places two pads against the left ventricle underneath the mitral valve annulus, using a string which is passed through the left ventricular chamber connecting the two pads. Since the device is in contact with blood within the heart, risk of thromboembolism is significantly increased. A similar device is described in “Tensioning device and system for treating mitral valve regurgitation” by Elliot Bloom et al., PCT International Publication No. WO 2004/112658 A1 (29 Dec. 2004). Again, the tensioning device is in contact with the blood within the heart.
In U.S. Pat. No. 6,293,906 for “Delivery Of Cardiac Constraint Jacket” by John C. Van den Hoek and Jody L. Rivers, a cardiac constraint jacket is described which is formed of flexible material defining a volume between an open upper end and a lower end, and adapted for an apex of a patient's heart to be inserted into the volume through the open upper end and for the jacket to be slipped over the heart. The jacket can be used in early stages of congestive heart disease. For patients having heart enlargement as a result of viral infection, the jacket permits constraint of the heart for a sufficient time to permit the viral infection to pass. In addition to preventing further heart enlargement, the jacket treats valvular disorders by constraining circumferential enlargement of the valvular annulus and deformation of the ventricular walls. Once placed on the heart, the jacket is adjusted to a snug fit on the heart during diastole.
International Publication No. WO 2004/043265 for “Devices And Methods For Heart Valve Treatment” by Robert M. Vidlund et al. describes methods and devices for improving the function of mitral valves by positioning an implantable device outside and adjacent the heart wall such that the device alters the shape of the heart wall acting on the valve by applying an inward force and/or by circumferential shortening, and may increase coaption of the leaflets to reduce regurgitation. In the General Description of Exemplary Implant Devices section of this patent application, an implantable device including two or more anchor ends with an interconnecting member connected therebetween is described. The anchor ends may be configured to permanently or releasably attach to the outside of the heart wall. The interconnecting member may be selectively tightened or loosened to correspondingly affect the tension between the anchor ends. A protrusion may be connected to the interconnecting member between the anchor ends, or the anchor ends may be utilized without the use of a protrusion. With or without the protrusion, the interconnecting member may be generally flexible to conform to the outer surface of the heart.
Accordingly, it is an object of the present invention to provide a device for reducing mitral valve regurgitation resulting from cardiac dilation and/or tethering of the papillary muscle.
Another object of the invention is to provide a device for reducing cardiac functional mitral valve regurgitation resulting from cardiac dilation and/or tethering by the papillary muscle where the device is not in contact with blood of the patient after placement in the body.
Still another object of the invention is to provide device for reducing cardiac functional mitral valve regurgitation resulting from cardiac dilation and/or tethering of the papillary muscle which does not require cardiopulmonary bypass for installation thereof.
Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.